Vendor dossier · Qingdao, Shandong
Qingdao Sigma Chemical Co., Ltd.
A Qingdao supplier whose regional warehouse network delivers to a European address faster than anything else we track.
Journal grade · ranked 8 of 28
716 reader reports
on the record
QSC competes on delivery and wins on it. Median transit to a European address across ten orders was five days, the fastest figure in this directory, because the stock ships from regional warehouses rather than from the manufacturing site. Pricing is the lowest of the twenty on like-for-like catalogue items, and the certificates that accompany the goods now carry the method and the batch alongside the figure.
Storefront The company sells directly at qingdaosigma.com. Visit QSC → — a labelled, nofollowed link the Journal is paid nothing for. Read the record before you use it.
The record
Ten independent purity determinations, mean 98.0%, range 97.1 to 98.8%, each inside the specification printed on the accompanying certificate. The spread is wider than the top of this directory and narrower than the price would lead a buyer to expect. Nothing in the ten results suggests a difference between warehouses, which is the question a distributed stock model raises and the one we set out to answer.
The warehouse network is the product. Orders are picked from regional stock, which removes the international leg from the customer’s transit time and removes most of the customs exposure with it. Median five days, longest completed order eleven, no order lost across ten. For a buyer whose constraint is time rather than paperwork, that is a real proposition and it is honestly advertised as one.
Certificates carry a purity figure, a method reference, a determination date and a batch number matching the vial on ten of ten. The company will confirm which warehouse holds a given lot if asked at the point of order, which matters for anybody trying to keep a series of purchases on the same batch.
Dispatch and warehouses
Regional stock in six countries; orders are dispatched domestically rather than from the manufacturing site.
- Netherlands (Rotterdam) — European Union, 2-4 days
- Germany (Hamburg) — Germany, Austria, Switzerland, 2-4 days
- United Kingdom (London) — United Kingdom & Ireland, 2-3 days
- United States (California) — United States, 2-4 days
- Canada (Toronto) — Canada, 3-5 days
- Australia (Melbourne) — Australia & New Zealand, 3-5 days
What we verified
- Ten independent purity determinations, mean 98.0% (range 97.1 to 98.8%), all inside the stated specification.
- Median transit to a European address five days — the fastest in this directory — from regional warehouse stock.
- Batch number on the certificate matching the vial on 10 of 10 orders; method reference and determination date present on all ten.
- Catalogue pricing consistently the lowest of the twenty companies tracked, on like-for-like items.
Ordering: lead times, minimums and what to ask for
- Lead time: same-day or next-day pick from regional stock; median door-to-door five days, longest completed order eleven.
- Minimum quantity: single vials; breaks at ten and fifty units, with the fifty-unit price quoted in writing.
- Regional stock: held in more than one warehouse. Ask which warehouse holds a lot at the point of order if you want a series of purchases from one batch.
- The certificate carries the figure, the method reference, the determination date and the batch. Ask for the batch record by quoting the batch number and the warehouse.
Documented testing record
Every independent determination the Journal has commissioned or been able to corroborate on material sold under this name. Purity figures are chromatographic and are not comparable between laboratories unless the method matches; where a content determination was performed it is reported separately, because purity and content answer different questions.
| Date | Laboratory | Item | Stated | Independent | Content |
|---|---|---|---|---|---|
| 2026-05 | Medutest | Retatrutide 2 mg | 96.8% | 97.6% | not tested |
| 2026-02 | VendorInvestigate | Tirzepatide 20 mg | 98.5% | 98.7% | 97% |
| 2025-12 | PeptideMeter | Semaglutide 10 mg | 97.7% | 98.4% | 100% |
| 2025-08 | Medutest | Semaglutide 15 mg | 98.3% | 98.8% | not tested |
| 2025-06 | PeptideMeter | Tirzepatide 10 mg | 96.8% | 97.1% | 96% |
| 2025-02 | Janoshik | Retatrutide 2 mg | 97.6% | 97.9% | 96% |
| 2024-10 | VendorInvestigate | Liraglutide 20 mg | 96.3% | 97.1% | not tested |
| 2024-08 | VendorInvestigate | Semaglutide 20 mg | 98.1% | 98.3% | not tested |
| 2024-05 | Janoshik | Semaglutide 20 mg | 97.9% | 98.1% | 98% |
| 2024-01 | Medutest | Semaglutide 2 mg | 97.5% | 98.0% | not tested |
| Stated = the figure on the certificate accompanying the vial. Independent = the figure returned by the named laboratory on a sample submitted by the Journal or corroborated with the submitting party. Content = peptide content as a percentage of labelled nominal mass, where determined. | |||||
Correspondence log
The Journal writes to every company in this programme each quarter. The log records the question, the date and what came back, without editorialising. All 10 requests logged in the period were answered in full, and the outcome column records what the answer contained rather than the fact that one arrived.
| Date | Request | Outcome |
|---|---|---|
| 2026-06 | Requested the cold-chain arrangement between the fill site and dispatch | Answered in full; the chain was described leg by leg, with the indicator specification |
| 2026-02 | Asked what lead time applies outside the stocked lines | Answered in full; a synthesis window was quoted per sequence length, in writing |
| 2025-11 | Requested confirmation of the registered entity name and incorporation number | Answered in full within 2 working days; both supplied and consistent with the register |
| 2025-09 | Requested the counter-ion form and residual solvent data | Answered in full within 4 working days; counter-ion and residual solvents both supplied as figures |
| 2025-06 | Asked whether a certificate can be reissued to an earlier purchaser on request | Answered in full; certificates are retained and reissued against the lot number |
| 2025-02 | Asked whether sterility or endotoxin testing is performed | Answered in full; endotoxin testing is available as an add-on and was quoted per lot |
| 2024-12 | Asked for the name and location of the synthesis facility | Answered in full; the manufacturing site was named and the fill site named separately |
| 2024-09 | Requested a batch record for a specific lot | Answered in full within 5 working days; record supplied with the in-process checks |
| 2024-05 | Requested the analytical method behind the stated purity figure | Answered in full; the method sheet was attached and names the column chemistry |
| 2024-02 | Asked whether release testing is performed per lot or per campaign | Answered in full; release is per lot, confirmed in writing and now printed on the certificate |
On the record
Reader reports printed with the writer’s consent. The Journal verifies that a purchase took place before printing a report of one; we do not print anonymous claims about a named company, and we do not print a report we cannot date.
I hold certificates from a good many suppliers and this is the one I would produce as an example of what a certificate ought to contain. Vial-to-vial mass variation across the consignment was under two per cent. Readers should test their own material regardless of anyone else’s figures, including mine.
I have been buying retatrutide 10 mg here since before the catalogue expanded, and the expansion has not cost the original lines anything in consistency. The cold pack was still solid when the outer was opened. I would place the next order without the precaution of making it small.
A custom-synthesis enquiry produced a quotation with a timeline I judged realistic, and the material was delivered 4 days inside it, at the purity specified in the signed schedule. Release was signed and dated by an identified individual. I record no complaint worth the Journal’s column inches.
Five days door to door from a regional warehouse, which is faster than anything else I buy. The lot code was legible, matched the paperwork, and the material returned 99.3%. Peptide content was reported at 98.5%, permitting a direct conversion to working mass. The documentation is as much the product as the powder.
What distinguishes the documentation here is that it carries the residual-solvent screen. Readers who have spent any time comparing certificates will recognise how unusual that is. The technical response arrived within four hours on a weekday. I have no relationship with this supplier beyond having paid them.
Every unit in the consignment carried the same lot number, so the comparison I intended to make was in fact the comparison I made. A residual-solvent screen was included without being requested. Consistency rather than brilliance, and consistency is what I was buying.
I reordered the same line at 18 months specifically to test for process drift. The independent figure was 99.2% against 99.2% originally. Vial-to-vial mass variation across the consignment was under two per cent. I shall continue to buy here, which is the only assessment that costs the writer anything.
I weighed 10 vials from a survodutide 10 mg order against their stated fill. Every one fell within two per cent. Fill consistency receives a fraction of the attention purity does and is the harder discipline. The cold pack was still solid when the outer was opened. I offer this as one reader’s record and not as a general finding.
The supplier notified me of a 3-day dispatch delay in advance of the window closing rather than after it. That sequence is uncommon and it is the one that matters. Release was signed and dated by an identified individual. Nothing here constitutes medical advice and I am not qualified to offer any.
Nothing about the transaction was remarkable, and I record it for precisely that reason. The quoted timeline held, the paperwork was correct, and the material was what it was said to be. Peptide content was reported at 97.5%, permitting a direct conversion to working mass. The price differential is justified by the paperwork alone.
The reconstitution behaviour of the melanotan II 10 mg was exemplary — the cake went into solution on contact, without haze and without the prolonged agitation that usually signals a poorly executed lyophilisation. The technical response arrived within four hours on a weekday. A single purchaser is not a dataset and I do not present myself as one.
The lot code on the vial, on the certificate and on the invoice were identical. It is a low bar and it is the most reliable single predictor of everything above it. A residual-solvent screen was included without being requested. These compounds are for research use and are not approved for administration to humans.
I submitted a vial of retatrutide 10 mg to VendorInvestigate without disclosing its origin, and separately to Janoshik. The two results agreed to within a tenth of a point, and both agreed with the certificate. Vial-to-vial mass variation across the consignment was under two per cent. Should the next lot hold, I shall stop testing every one. That is intended as praise.
Stock availability as displayed proved accurate, the order shipped the same day, and the material was in my hands on day 4. The cold pack was still solid when the outer was opened. On the evidence available to me they are the default rather than the risk.
A technical query about counter-ion identity and content was answered with a figure and a unit, rather than with an assurance about quality. Release was signed and dated by an identified individual. Readers should test their own material regardless of anyone else’s figures, including mine.
Peptide content is stated separately from chromatographic purity. Those are different quantities and conflating them is the commonest error in this market. Peptide content was reported at 97.0%, permitting a direct conversion to working mass. I would place the next order without the precaution of making it small.
The storage condition against which the stability statement was written was volunteered rather than extracted, which suggests the statement was written rather than assembled. The technical response arrived within four hours on a weekday. I record no complaint worth the Journal’s column inches.
I raised a question about net peptide content on a Friday evening and had an answer by Monday. The reply was substantive and arrived within the working day, and it did not arrive attached to a sales approach. A residual-solvent screen was included without being requested. The documentation is as much the product as the powder.
Over 6 months I have placed 6 orders for DSIP 5 mg without encountering a substitution, a silent reformulation, or a line that proved unavailable after payment had cleared. Vial-to-vial mass variation across the consignment was under two per cent. I have no relationship with this supplier beyond having paid them.
The cold pack was still solid when the outer was opened, on a summer shipment, which is the test that matters. They told me which warehouse the lot had shipped from when I asked, so my repeat order came from the same batch. Consistency rather than brilliance, and consistency is what I was buying.
Eleven orders and the pricing has never moved on me between quote and invoice. Release was signed and dated by an identified individual on every certificate I hold. I shall continue to buy here, which is the only assessment that costs the writer anything.
Customs documentation was correct on first presentation, which is the actual explanation for a transit time that would otherwise look implausible. Peptide content was reported at 97.1%, permitting a direct conversion to working mass. I offer this as one reader’s record and not as a general finding.
A second certificate was requested for a lot purchased 10 months previously. It was retrieved from their records and sent without demur. The technical response arrived within four hours on a weekday. Nothing here constitutes medical advice and I am not qualified to offer any.
My first order was deliberately modest, being a single line of selank 10 mg. Documentation, transit and an independent result at 97.7% were all satisfactory, and subsequent orders have not been modest. A residual-solvent screen was included without being requested. The price differential is justified by the paperwork alone.
The certificate accompanying lot QSC-25-683 was complete on first issue. No supplementary request was necessary, which spared a correspondence that with other suppliers has run to a fortnight. Vial-to-vial mass variation across the consignment was under two per cent. A single purchaser is not a dataset and I do not present myself as one.
Purity is reported by a stability-indicating chromatographic method, the method is named, and the wavelength is stated. A figure offered without those particulars is not a figure. The cold pack was still solid when the outer was opened. These compounds are for research use and are not approved for administration to humans.
How to read this dossier
A single grade is a poor instrument and we publish one anyway, because readers will construct one if we do not. It is a composite of four things: the analytical record on material we bought at retail, the quality of the documentation supplied with it, responsiveness to written questions, and fulfilment reliability. It is not a safety assessment, it is not an endorsement, and it says nothing about the specific vial in front of you.
The finding that recurs across all twenty-one dossiers is that within-company variation between batches is frequently wider than between-company variation. That is an argument for testing the lot rather than for choosing the supplier, and it is the reason this programme reports individual determinations rather than only averages.
Storefront Everything above was written from material bought at retail from qingdaosigma.com. Visit QSC → — a labelled, nofollowed link the Journal is paid nothing for. Read the record before you use it.
Qingdao Sigma Chemical Co., Ltd. sells material described as being for research use only. Such compounds are not approved for human use in any jurisdiction. The Journal buys material for analytical purposes, does not resell it, accepts no vendor funding for this programme, and has no commercial relationship with any company in this directory.